Abstract

Membrane filtration has been gaining great attention in water and wastewater treatments processes because of its high-performance efficacy, modular design, and smaller physical footprint. Thanks to special membrane materials and structure, osmosis processes are widely used in water desalination and water reuse processes. Aside from their high performance of osmosis processes, they inevitably do suffer from membrane fouling and biofouling during treatment processes that significantly decrease water treatment performance and final product quality.
Two different biocidal nanomaterials and their combinations were used in this project for the modification of membrane surfaces and the development of biocidal membranes: silver nanoparticles (AgNPs) and graphene oxide nanosheets (GO).
GO/Ag nanocomposite functionalization of TFC FO membranes provides an efficient antimicrobial surface that has more desirable characteristics than those with only GO or Ag NPs. Also, the higher hydrophilicity of the resulting membranes, the low material cost, and the ease of preparation (dip coating method) offer a more efficient approach than other modification methods. In comparison to the formation of AgNPs on pristine TFC FO membranes, the in situ formation of AgNPs on the GO-modified membrane surface resulted in greater silver loading, higher and longer lasting ion-release, and more effective antimicrobial properties.
The regeneration of GO-Ag-modified membranes was also examined. Modified membranes were kept in DI water for seven days to emulate depletion. AgNPs were successfully formed using an in-situ procedure on the surface of the membranes, identical to the initial membrane formation. Results show that membrane hydrophilicity and its antimicrobial ability decreased after the releasing process, however, the regeneration process allowed the membrane to nearly regain the properties seen in the freshly modified membrane. The simple regeneration method developed in this study will allow on-site modification and regeneration of different types of industrial membrane modules (hollow fiber, spiral wound).